Many events do not begin until 26 July, but Jenna Randall and Olivia Allison compete in the synchro from 18 July.

The open water competition, due to start on Sunday morning, has been delayed by two days.

The start and finish wharf in the coastal town of Ostia was damaged by stormy weather and high water.

I have to dive at my very best and put the pressure on them so that maybe they make mistakes

Tom Daley

Organisers considered the possibility of relocating the event, but have instead opted to delay the opening 5km men's and women's races until Tuesday.

A seven-strong British team led by Olympic silver medallist Keri-Anne Payne is competing although fellow medallists David Davies and Cassie Patten are missing.

Plymouth diver Daley has already improved his personal best on three occasions this year, having finished seventh in his final at the 2008 Beijing Games.

He won gold in his last appearance, in Fort Lauderdale in May, with a personal best of 554.90 - a score that would have been good enough for him to claim gold in Beijing.

But he will have to perform exceptionally well to make his relatively low tariff - the degree of difficulty of his dives - match up to the scores his competitors can produce.

"It is going to be very, very tough to get a medal because my tariff is lower than all the other divers," said Daley.

"After the World Championships I'll be working on some new dives to get my tariff up. But for now all the other divers will obviously have higher tariffs so I have to hope they make some mistakes.

"The thing I have to do is dive at my very best and put the pressure on them so that maybe they make those mistakes and I can take advantage."

The diving events at Rome's Foro Italico will be held outdoors, an unusual challenge for the divers as most events are held indoors.

Reigning Olympic champion Mitcham could stop a Chinese sweep

Daley, whose Fort Lauderdale success came at an outdoor pool, said: "The Fort Lauderdale meet gave me a lot of confidence. To get a personal best at an outdoor pool is something that I was very happy with.

"It is very different diving outdoors than indoors. It is hard to know exactly where you are and which way you are facing because the sky is the same colour as the water.

"But it wouldn't be the end of the world if I didn't get a medal in Rome. I am not going there expecting to get a medal but I go there knowing that if I dive at my absolute best then I will get one."

While Daley is the focus of British attention, it is expected that China will sweep the board in the diving competition.

Chinese divers won seven out of eight gold medals on home territory last year, and in the 2007 Worlds they claimed nine out of 10.

However, on both occasions they failed to capture the men's 10m platform gold - Daley's event.

Australian Mitcham will go into that event as favourite following victory in Beijing, where he snatched an unlikely gold by producing the highest ever single dive score of 112.10 on his final effort, while China's Zhou Luxin produced his worst effort of the Games with a 74.80.

Zhou will be back in Rome to try to make amends as China sticks with its so-called 'Dream Team' of 10 athletes from Beijing.

But China's star attraction will be four-time Olympic champion Guo Jingjing, who will compete in her sixth, and possibly last, Worlds.

Please turn on JavaScript. Media requires JavaScript to play.

Meet Britain's top synchronised swimmers

Synchronised swimmers Randall and Allison may not be realistic medal prospects, but Randall has set her sights on an appearance in the final at the Stadio Pietrangeli temporary pool.

"At the Worlds two years ago we were 20th, and now we're 14th," she told BBC Sport. "Hopefully we'll get into the final, which is the top 12, because we've improved quite a lot."

For the first time in more than a decade Britain will participate in solo, duet and team as well as combination events.

Russia - where the top British pair have been training - will be the team to beat in synchro, having claimed both the duet and team titles for the third Games in a row in Beijing.

But Gemma Mengual leads a strong Spanish team, while Italy will be hoping to benefit from the support of home fans.

Japan are perennial medal contenders while China, led by twin sisters Jiang Tingting and Jiang Wenwen, are hoping to build on their bronze medal performance in Beijing.

We would love to come away with a few medals but we have to be realistic

Mark PerryGB open water performance manager

Mark Perry, performance manager for the British open water team, has admitted he does not expect a glut of medals in the absence of Davies and Patten.

"We're mainly going to the World Championships for the experience - everything now is about building a team and working toward London 2012 which is our main goal," said Perry last month.

"We're obviously going in minus two medallists, but we still have Keri-Anne Payne so we are hoping for good things from her.

"We would love to come away with a few medals but we have to be realistic. We can't expect a repeat of Beijing."

In the water polo competition, the Balkan men's teams of Serbia, Montenegro and Croatia are expected to compete with the US and Spain for medals, while the American, Australian and Russian women's teams are favourites to reach the podium.

The likes of Michael Phelps, Aaron Peirsol, Rebecca Adlington and Dara Torres will compete in Rome once their events start, from 26 July, but Britain's Kate Haywood has been forced to withdraw through injury.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.